PROJECT SUMMARY/ABSTRACT Patients with new episodes of venous thromboembolism (VTE) are at an elevated risk for adverse drug events (ADEs). Although trial data suggest that direct oral anticoagulants (DOACs) are safer than warfarin, data from non-trial setting suggests problems with dosing and other medication appropriateness criteria (administration, drug- drug interactions, duration, etc.) in a full 60% of patients prescribed DOACs. This is particularly concerning for patients with venous thromboembolism (VTE) diagnosed and discharged without hospitalization, i.e. the ambulatory VTE population, and prescribed direct oral anticoagulants. The ambulatory VTE population includes most patients with deep vein thrombosis (DVT) and many patients with pulmonary embolism. Unlike patients with atrial fibrillation, who typically receive follow-up with a cardiologist, or patients attending warfarin clinics, ambulatory VTE patients prescribed DOACs do not have established pathways for follow-up. They also do not typically have consultation by a clinical pharmacist as a hospitalized patient often does. Recently the Anticoagulation Forum, a multidisciplinary nonprofit organization focused on anticoagulation issues, published the DOAC Checklist for Optimal Care Transitions (DOAC Checklist) to elaborate the steps required to ensure a safe transition of care in patients prescribed DOACs for treatment of VTE. These steps include evaluation of the appropriateness of DOAC, confirmation of the affordability and access of DOAC prescribed, patient education, telephone access to anticoagulation expertise, consolidated documentation and communication to primary care provider, and renal and hepatic function monitoring. We propose operationalizing the items of the DOAC Checklist to create a comprehensive intervention delivered by clinical pharmacists and a pharmacy technician with the goal of preventing DOAC-related clinically important medication errors which includes preventable ADEs, ameliorable ADEs (ADEs in which the severity or duration could have been reduced), and potential ADEs (medication errors with the potential to cause harm). Our proposal includes the following specific aims: (1) operationalize the items of the AC Forum's DOAC checklist to create a comprehensive, standardized intervention delivered by clinical pharmacists for ambulatory VTE patients prescribed DOACs; (2) measure the difference in clinically important medication errors with DOAC for 500 patients randomized to intervention and control arms; (3) conduct a process evaluation assessing fidelity, adaptation, mechanisms of impact and the influence of contextual factors on implementation of our intervention; and (4) create a plan for disseminating study findings. Given the growth of the ambulatory VTE population prescribed DOACs, the associated risks with this class of medications, and the lack of defined pathways for these patients, our care transition intervention has the potential for enormous impact in preventing clinically important medication errors and improving the quality of care transition, patient knowledge, and medication adherence.